A invested a sum of Rs.20000.1 for 2 years and 10 days at the rate of 11% p.a.…
2023
A invested a sum of Rs.20000.1 for 2 years and 10 days at the rate of 11% p.a. at compound interest. The amount he receives after two years again invested for same time at same interest rate in simple interest. Find the approximate simple interest he received.
- A.
Rs.5421
- B.
Rs.5309
- C.
Rs.5390
- D.
Rs.5445
- E.
Rs.5530
Attempted by 3 students.
Show answer & explanation
Correct answer: A
Concept
Compound interest grows a principal multiplicatively: the amount after n years at rate R% per annum is A = P×(1 + R/100)n. Simple interest grows it additively: SI = P×R×T/100, where the principal P stays fixed over time. Here the matured compound amount becomes the fresh principal for the simple-interest stage.
Reading the data
The figures “Rs.20000.1” and the trailing “10 days” are exam padding: with a literal 2-years-10-days reading the interest works out near Rs.5512, which is not among the choices, whereas clean 2-year periods on a round Rs.20000 land exactly on an offered value. So the intended computation uses P = Rs.20000 over 2-year periods.
Application
Compound amount for 2 years: A = 20000×(1.11)2 = 20000×1.2321 = Rs.24642.
Reinvest this Rs.24642 at simple interest, 11% p.a., for 2 years.
SI = 24642×11×2/100 = 24642×0.22 = Rs.5421.24 ≈ Rs.5421.
Cross-check
One year's simple interest on Rs.24642 is 24642×0.11 = Rs.2710.62; doubling gives Rs.5421.24, confirming the rounded Rs.5421 — the only offered value reachable by the standard method.